1. Field of the Invention.
This invention relates to nonimpact thermal printing apparatus for recording information on plastic card stock such as plastic credit cards.
2. Description of the Prior Art.
A number of systems exist for recording visual information such as characters or symbols onto sheet material such as paper or similar lightweight materials. A common system of applying the information is through the use of thermal print heads utilizing thin or thick film semi-conductor material as shown in U.S. Pat. No. 3,496,333. That patent shows print elements which have a semi-conductor substrate formed with a plurality of thermally independent elements or islands which project slightly from a semi-conductor substrate. Each independent element includes a semi-conductor heating section which can be individually selected using known circuit means to cuse the individual elements to heat in a pattern which is to be printed.
In U.S. Pat. No. 3,855,448 such a print head is shown in a printer which applies printed information to recording paper free of thermal sensitive material. A printing foil is used which has a heat resistant backing layer upon which a thin film of adhesive resin of a low melting point is disposed. The foil is positioned between the thermal head and recording paper. The print head selectively melts portions of the adhesive resin and releases them from the backing layer to thereby transfer molten resin to the recording paper to accomplish printing on the recording paper. Although such printers have found widespread use for applying printed material to conventional recording paper, they have not been used heretofore in printing on relatively thick and inflexible materials such as plastic credit cards, for example.